197 lines
6.6 KiB
Go
197 lines
6.6 KiB
Go
// Copyright 2015 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package trie
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import (
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"fmt"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/log"
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)
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// SecureTrie wraps a trie with key hashing. In a secure trie, all
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// access operations hash the key using keccak256. This prevents
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// calling code from creating long chains of nodes that
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// increase the access time.
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//
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// Contrary to a regular trie, a SecureTrie can only be created with
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// New and must have an attached database. The database also stores
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// the preimage of each key.
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//
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// SecureTrie is not safe for concurrent use.
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type SecureTrie struct {
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trie Trie
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hashKeyBuf [common.HashLength]byte
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secKeyCache map[string][]byte
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secKeyCacheOwner *SecureTrie // Pointer to self, replace the key cache on mismatch
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}
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// NewSecure creates a trie with an existing root node from a backing database
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// and optional intermediate in-memory node pool.
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//
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// If root is the zero hash or the sha3 hash of an empty string, the
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// trie is initially empty. Otherwise, New will panic if db is nil
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// and returns MissingNodeError if the root node cannot be found.
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//
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// Accessing the trie loads nodes from the database or node pool on demand.
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// Loaded nodes are kept around until their 'cache generation' expires.
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// A new cache generation is created by each call to Commit.
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// cachelimit sets the number of past cache generations to keep.
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func NewSecure(root common.Hash, db *Database) (*SecureTrie, error) {
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if db == nil {
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panic("trie.NewSecure called without a database")
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}
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trie, err := New(root, db)
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if err != nil {
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return nil, err
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}
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return &SecureTrie{trie: *trie}, nil
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}
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// Get returns the value for key stored in the trie.
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// The value bytes must not be modified by the caller.
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func (t *SecureTrie) Get(key []byte) []byte {
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res, err := t.TryGet(key)
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if err != nil {
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log.Error(fmt.Sprintf("Unhandled trie error: %v", err))
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}
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return res
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}
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// TryGet returns the value for key stored in the trie.
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// The value bytes must not be modified by the caller.
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// If a node was not found in the database, a MissingNodeError is returned.
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func (t *SecureTrie) TryGet(key []byte) ([]byte, error) {
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return t.trie.TryGet(t.hashKey(key))
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}
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// Update associates key with value in the trie. Subsequent calls to
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// Get will return value. If value has length zero, any existing value
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// is deleted from the trie and calls to Get will return nil.
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//
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// The value bytes must not be modified by the caller while they are
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// stored in the trie.
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func (t *SecureTrie) Update(key, value []byte) {
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if err := t.TryUpdate(key, value); err != nil {
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log.Error(fmt.Sprintf("Unhandled trie error: %v", err))
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}
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}
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// TryUpdate associates key with value in the trie. Subsequent calls to
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// Get will return value. If value has length zero, any existing value
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// is deleted from the trie and calls to Get will return nil.
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//
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// The value bytes must not be modified by the caller while they are
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// stored in the trie.
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//
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// If a node was not found in the database, a MissingNodeError is returned.
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func (t *SecureTrie) TryUpdate(key, value []byte) error {
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hk := t.hashKey(key)
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err := t.trie.TryUpdate(hk, value)
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if err != nil {
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return err
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}
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t.getSecKeyCache()[string(hk)] = common.CopyBytes(key)
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return nil
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}
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// Delete removes any existing value for key from the trie.
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func (t *SecureTrie) Delete(key []byte) {
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if err := t.TryDelete(key); err != nil {
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log.Error(fmt.Sprintf("Unhandled trie error: %v", err))
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}
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}
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// TryDelete removes any existing value for key from the trie.
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// If a node was not found in the database, a MissingNodeError is returned.
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func (t *SecureTrie) TryDelete(key []byte) error {
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hk := t.hashKey(key)
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delete(t.getSecKeyCache(), string(hk))
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return t.trie.TryDelete(hk)
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}
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// GetKey returns the sha3 preimage of a hashed key that was
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// previously used to store a value.
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func (t *SecureTrie) GetKey(shaKey []byte) []byte {
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if key, ok := t.getSecKeyCache()[string(shaKey)]; ok {
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return key
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}
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key, _ := t.trie.db.preimage(common.BytesToHash(shaKey))
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return key
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}
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// Commit writes all nodes and the secure hash pre-images to the trie's database.
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// Nodes are stored with their sha3 hash as the key.
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//
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// Committing flushes nodes from memory. Subsequent Get calls will load nodes
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// from the database.
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func (t *SecureTrie) Commit(onleaf LeafCallback) (root common.Hash, err error) {
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// Write all the pre-images to the actual disk database
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if len(t.getSecKeyCache()) > 0 {
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t.trie.db.lock.Lock()
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for hk, key := range t.secKeyCache {
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t.trie.db.insertPreimage(common.BytesToHash([]byte(hk)), key)
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}
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t.trie.db.lock.Unlock()
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t.secKeyCache = make(map[string][]byte)
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}
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// Commit the trie to its intermediate node database
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return t.trie.Commit(onleaf)
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}
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// Hash returns the root hash of SecureTrie. It does not write to the
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// database and can be used even if the trie doesn't have one.
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func (t *SecureTrie) Hash() common.Hash {
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return t.trie.Hash()
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}
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// Copy returns a copy of SecureTrie.
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func (t *SecureTrie) Copy() *SecureTrie {
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cpy := *t
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return &cpy
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}
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// NodeIterator returns an iterator that returns nodes of the underlying trie. Iteration
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// starts at the key after the given start key.
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func (t *SecureTrie) NodeIterator(start []byte) NodeIterator {
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return t.trie.NodeIterator(start)
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}
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// hashKey returns the hash of key as an ephemeral buffer.
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// The caller must not hold onto the return value because it will become
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// invalid on the next call to hashKey or secKey.
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func (t *SecureTrie) hashKey(key []byte) []byte {
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h := newHasher(nil)
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h.sha.Reset()
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h.sha.Write(key)
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buf := h.sha.Sum(t.hashKeyBuf[:0])
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returnHasherToPool(h)
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return buf
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}
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// getSecKeyCache returns the current secure key cache, creating a new one if
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// ownership changed (i.e. the current secure trie is a copy of another owning
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// the actual cache).
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func (t *SecureTrie) getSecKeyCache() map[string][]byte {
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if t != t.secKeyCacheOwner {
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t.secKeyCacheOwner = t
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t.secKeyCache = make(map[string][]byte)
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}
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return t.secKeyCache
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}
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